Spring collet



Dec. 7, 1943.

H, H. SIMPSON 2,335,974

SPRING COLLEI" Filed April 17, 1942 JNVENTOR. 5/MP50/v A TTOIQNEY Patented Dec. 7, 1943 UNITED STATES PATENT OFFICE SPRING COLLET Homer H. Simpson, Woodsi'de, N. Y. Application April 17, 1942, Serial No. 439,323

(Cl. 58 l15) Claims.

This invention relates generally to spring collets. More particularly my invention is concerned with an improved method and means for attaching springs to collets.

One of the objects of my invention is to provide an improved spring collet construction by means of which a spring may be automatically trued and secured in position.

Another object of my invention is to provide an improved method and means for automatically securing springs to collets which shall be characterized by the simplicity of the construction of the collet and of the ease with which a spring may be attached thereto.

Other objects of my invention will hereinafter be pointed out or will become evident from the following description.

In the accompanying drawing,

Fig. 1 is a side elevational view of a spring collet constructed in accordance with my invention;

Fig. 2 is a top plan view thereof;

Fig. 3 is a bottom plan view thereof, illustrating the hair spring as mounted on the collet; and

Fig. 4 is a view similar to Fig. 3 but illustrating the automatic clamping action which attaches the spring to the collet when the collet is mounted on a shaft.

Referring now in detail to the drawing, I have shown a collet l0 constructed in accordance with my invention and adapted to have automatically attached thereto a spring, such as, for example, a watch hair spring S of the customary type. The said collet may be made of the customary metallic material and provided with a central opening H for attaching the same to a shaft. The collet III is designed to be frictionally received on the shaft by means of slot l2 cut through transversely from the periphery to the opening II. The action of the slot I2 is such that when the collet is placed on the shaft the opening II will be permitted to resiliently expand so as to frictionally grip the shaft.

In accordance with my invention I provide a circumferential groove l4 slightly spaced from the bottom surface a of the collet, as clearly shown in Fig. 1. The width of this groove I4 is substantially equal to the width of the spring which it is desired to attach to the collet. The annular surface lllc, extending from the groove M to the top surface [0b of the collet, is tapered with a continual uniform taper throughout as indicated in Fig. 1. At a point less than 180 degrees from the slot I2, I provide a transverse notch I5. This notch extends preferably to a depth approximately two thirds of the wall thiclrness of the collet surrounding the opening H. I have found that good results are obtained when the notch I5 is disposed at about degrees from the slot l2, or between approximately 45 degrees to approximately degrees from the slot I2. I have also discovered that the said notch would be least effective when placed at a point degrees from the slot l2, due to the fact that when the collet is placed on the shaft a break may occur at the notch since the greatest expanding strain for the collet would be at such point.

The spring S which may be any ordinary type of spring, such as a hair spring of a watch, is provided at the inner end thereof with an angularly bent portion IS. The spring S is attached to the collet in the following manner. The portion l6 thereof is placed within the notch l5, after the inner convolutions of the spring have been spread out to equal the diameter of the top surface [0b of the collet. Then, with any suitable instrument the spring is slidably moved along the tapered surface I00 of the collet until it snaps into the groove l4. When this occurs the spring has been automatically trued because of the fact that the groove I4 prevents lateral displacement of the spring. The spring portion l6 continues to remain in the notch [5 as shown in Fig. 3 of the drawing. In Fig. 4 I have shown the collet H] as it appears when frictionally mounted on a shaft 20. It is noted that due to the expansion of the opening I I and the spreading apart of the slot 12 to resiliently accommo date itself to the diameter of the shaft l2, the walls of the notch I 6 will move towards each other to clamp and hold the spring portion I6 therebetween.

It is thus seen from the above described construction that the spring S which had been automatically trued when it was received in the groove I4 has also become automatically attached to the collet so that it will not move from position either laterally or axially.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the construction which I now consider to represent the best embodiment thereof, but I desire to have it understood that the construction shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. The combination with a split collet having a top wall, a bottom wall, and an annular side wall interconnecting said top and bottom walls, the split being such as to make the collet C- shaped, the said split collet being adapted to be placed on a shaft which is oversize with respect to the inner surface of the collet, and in which said side wall is provided with an annular peripheral groove spaced from said bottom wall and which is additionally provided with a notch ex tending inwardly from the periphery of said side wall and disposed transversely of said groove and which the said notch is located at a point on the periphery of said side wall less than 180 degrees from the split of said collet. V

3. The combination according to claim 1 in which the said notch is located at a point on the periphery of said side wall spaced from approximately 45 degrees to approximately 135 degrees from the split of said collet.

4. The combination according to claim 1 in which the said notch is located at a point on the periphery of said side wall spaced approximately 90 degrees from the split of said collet.

5. The method of fastening a hair spring to a G-shaped split collet having an annular groove in which the said side wall tapers down from said groove to said top wall, of a hair springor the like having an angularly bent portion at its inner end received in said notch and its inner coil received in said groove, 'so that when the collet is driven onto said shaft it will be expanded so as to cause the said angularly bent portion of said spring to be clamped and held in position between the walls of said notch.

2. The combination according to claim 1 in on the periphery thereof and a notch in the peripheral surface, which consists in angularly bending a portion adjacent the inner end of said spring, placing said bent portion in said notch,

placing the inner coil of the said spring in said annular groove driving said collet on a shaft which is oversize with respect to the inner surface of the collet to cause the said collet to expand and thereby to cause the walls of the said notch to automatically clamp the angularly bent portion of said spring therebetween.

HOMER H. SIMPSON. 

